The present invention relates to image forming apparatus such as copiers, facsimile machines, and printers.
Some image forming apparatus such as printers, copiers, and facsimile machines have the function of printing both sides of a printing medium such as paper.
FIGS. 10 and 11 are illustrations showing a structure of the neighborhood of paper ejection rollers of an image forming apparatus according to the related art having the double side printing function.
In the image forming apparatus having the double side printing function, a first paper ejection roller 150, a second paper ejection roller 160, and a third paper ejection roller 170 are provided at a terminal end section of a paper transport path. The first paper ejection roller 150 located in the middle can be rotated in two directions, i.e., forward and reverse directions. Each of the second paper ejection roller 160 and the third paper ejection roller 170 provided in positions opposite to each other on both sides of the paper ejection roller 150 is urged into contact with the first paper ejection roller 150 and is rotated in the forward direction relative to the first paper ejection roller 150.
In such a configuration, during double side printing, paper 90 which has been printed on one side thereof is switched back by the first and second paper ejection rollers 150 and 160 and is fed according to the next printing command to be subjected to the printing process again, whereby printing is performed on the other side.
Paper 90 on which printing has been completed on either single side printing basis or double side printing basis is sandwiched and transported by the first and third paper ejection rollers 150 and 170 to be ejected on to an ejected paper tray 130.
Since the first, second, and third paper ejection rollers 150, 160, and 170 rotate in two directions, i.e., forward and reverse directions, either of the pair of the first paper ejection roller 150 and the second paper ejection roller 160 and the pair of the first paper ejection roller 150 and the paper ejection roller 170 rotates in the direction opposite to the direction of ejecting the paper 90, i.e., the direction of feeding the paper into the apparatus, depending on their rotating directions.
As thus described, in the image forming apparatus having the double side printing function, since either of the pairs of paper ejection rollers rotates in the direction of feeding the paper into the apparatus from the gap between them, when someone attempts to collect paper stored in the ejected paper tray after printing, the paper can be caught between such paper ejection rollers.